HAN

Tuesday, September 07, 2004, 10:30 EDT (10:30 AM EDT)CDCHAN-00212-2004-09-07-UPD-NThe 38-year old man who died of Lassa fever in a New Jersey hospital traveled to the United States from Liberia via London. Further progress has been made in identifying passengers at risk of exposure to Lassa fever during travel on Continental Flight 29, which departed London Gatwick Airport on August 24 and arrived in Newark, N.J., at 3:20 pm on August 24.The plane was a Boeing 777-200, which has seats configured in groups of 3 with 9 seats and two aisles in each row. The case patient was seated in seat 21L, which is a window seat in economy class. Passengers seated within a six-foot radius of the case patient (i.e., passengers seated in seats F, J, K, L in rows 19-23) are considered at low risk for potential exposure, based on guidance outlined in the CDC HAN issued September 2, 2004.The airline has provided CDC the names of passengers who occupied seats 19 F-L, 20 F-L, 21 F-L, 22 F-L, and 23 F-L. CDC\u2019s Division of Global Migration and Quarantine is distributing this information to appropriate local and state health departments and national public health authorities, who in turn will advise passengers of their potential for exposure. In addition, these passengers will be advised to monitor their health for 21 days (i.e., the maximum incubation period) after their travel on Continental Flight 29. For airline passengers, this 21-day period ends September 14, 2004 and NOT September 18 as was incorrectly stated in the previous HAN. During this time, passengers should report a fever 101oF or greater to their local or state health department.Based upon currently available information and the configuration of the aircraft, only passengers seated in these 20 seat locations are considered to be at low risk of exposure. While no specific evaluation or monitoring is currently advised for persons seated in rows other than those listed above, any passenger who traveled on the implicated flight and who has concerns or develops a fever of 101oF or greater should seek medical evaluation and contact public health authorities.2004Lassa Fever, 2004VirusLassa viru

Characterization of a 50kW Inductively Coupled Plasma Torch for Testing of Ablative Thermal Protection Materials Using Non-Air Gases

Thermal protection systems have been a major area of study since the advent of space flight, but recent efforts towards crewed spaceflight missions have placed a new importance on the development of such systems. The 50 kW Inductively Coupled Plasma (ICP) Torch Facility at The University of Texas at Austin allows for rapid testing of high-temperature aerospace materials essential to the development of thermal protection systems in planetary re-entry applications. This ICP Torch Facility has been previously characterized using air as the test gas. However, planets of interest for future exploration have atmospheric compositions that differ from air, so testing heat shield materials in the presence of other gases is critical. To address this disparity between tested and actual environment, the current work characterizes the torch using various combinations of argon, CO2, and N2 by determining its operational range at various power settings, mass flow rates, and mixtures these gases. At each setting, the cold-wall heat flux is also measured to determine the range the torch is able to provide. Measurements indicate that using pure Ar gives the torch the largest operating range with regard to power setting and gas injection mass flow rate, and mixing argon into other gases drastically increases the stable operating range compared to the pure gas. Pure CO2 does not form a stable plasma discharge, but a mixture of 50% argon and 50% CO2 (by mass) provides stable operation up to 40 slpm total gas flow rate with a maximum heat flux of 98 W/cm2. Smaller percentages of CO2 allow the cold-wall heat flux to be increased to 110 W/cm2. Pure N2 forms a stable plasma discharge, but the operating range is very limited, providing stable operation up to 20 slpm total gas flow rate with a maximum heat flux of 110 W/cm2.Aerospace Engineering and Engineering Mechanic

Evaluations of some Toeplitz-type determinants

In this paper we evaluate some Toeplitz-type determinants. Let $n>1$ be an integer. We prove the following two basic identities: \begin{align*} \det{[j-k+\delta_{jk}]_{1\leq j,k\leq n}}&=1+\frac{n^2(n^2-1)}{12}, \\ \det{[|j-k|+\delta_{jk}]_{1\leq j,k\leq n}}&= \begin{cases} \frac{1+(-1)^{(n-1)/2}n}{2}&\text{if}\ 2\nmid n,\\ \frac{1+(-1)^{n/2}}{2}&\text{if}\ 2\mid n, \end{cases} \end{align*} where $\delta_{jk}$ is the Kronecker delta. For complex numbers $a,b,c$ with $b\not=0$ and $a^2\not=4b$, and the sequence $(w_m)_{m\in\mathbb Z}$ with $w_{k+1}=aw_k-bw_{k-1}$ for all $k\in\mathbb Z$, we establish the identity $$\det[w_{j-k}+c\delta_{jk}]_{1\le j,k\le n} =c^n+c^{n-1}nw_0+c^{n-2}(w_1^2-aw_0w_1+bw_0^2)\frac{u_n^2b^{1-n}-n^2}{a^2-4b},$$ where $u_0=0$, $u_1=1$ and $u_{k+1}=au_k-bu_{k-1}$ for all $k=1,2,\ldots$.Comment: 22 pages.Add parts (ii) and (iii) of Theorem 1.